Apparatus and method for edge sealing of foam boards

ABSTRACT

A method and machine for sealing at least one cut edge of a foam board is disclosed. The foam board has a top surface, a bottom surface and at least one cut edge extending between the top surface and the bottom surface. The cut edge is passed over a heated roller to soften the edge and then passed over a second roller having a temperature that is lower than the temperature of the first roller which seals the edge. The cut edge may be milled to square the edge relative to the top and bottom of the board before the cut edge is passed over the heated roller. Additional pairs of rollers may be provided to seal the top surface and the bottom surface of the foam board.

FIELD OF INVENTION

The present invention relates to devices and methods for sealing cutedges of foam boards.

BACKGROUND OF THE INVENTION

Boards made of polyvinyl chloride foam, polyurethane and other plasticfoams are often used for decking and non-load bearing exterior trimapplications such as beadboard, porch ceilings, door trim, window trim,or fascia and are also used in numerous other trim applications. Suchfoam trim board products typically have the look and function of premiumlumber. Foam trim boards can be cut and shaped using regular woodworkingtools.

Foam boards are often cut from large sheets of foam material. The formedsheets have a smooth outer surface, or skin. However, when the sheets offoam are cut to form foam boards, the cut edges of each board do nothave a smooth surface but have a cellular structure. The cut edges ofthe boards are noticeably different from the faces of the boards andpick-up dirt more readily. If the cells are quite small and the board ispainted, the differences between the cut edges and the faces are lessnoticeable. However, builders often prefer to use foam trim boards inapplications where the boards were not painted. Consequently, there is aneed for a foam board which can be cut from foam sheets and have smoothedges.

U.S. Pat. No. 5,240,751 discloses a decorative plastic trim strip usedin automobiles. The strips are made of thermoplastic material. The cutends of the strips are reshaped by a heated mold that is pressed againstthe end portion of the trim strip to create a smooth end. However, theuse of such a mold slows the manufacturing process by requiring each cutboard to be pressed within a mold after cutting of the boards. Moreover,the mold reshapes the cut edges of a product to have a curved end ortapered end. While molds may be useful for creating a smooth end on theend of a strip that is a few inches in width, it is not practical to usea mold to seal an edge that is six to twelve feet in length.

Further, such molding of the ends of trim pieces often creates flashing,which is plastic that extends from the edges of a trim piece after thepiece has been formed. Such flashing detracts from the aesthetic effectof the trim piece and may also create installation problems. Hence, theflashing typically must be removed from a piece of trim prior to sellingor using the trim piece.

A device and method are needed that can provide a skin or seal to thecut edges of foam boards. The sealed edge must be evenly sealed so thatthe sealed edge has little to no ability to trap dirt, unlike anon-sealed edge which has an overwhelming ability or tendency to trapdirt. The device and method preferably seal the cut edges to provide anedge having the same look and feel as the surface of the uncut portionsof a foam board so each foam board has a consistent appearance. Thedevice and method also preferably reduce, if not eliminate, theformation of flashing that may occur in sealing the cut edges of a foamboard.

SUMMARY OF THE INVENTION

We provide a method and machine for sealing the cut longitudinal edgesof a foam board in which the board is passed between a pair of heatedrollers and then between a second pair of rollers which are at a lowertemperature. The rollers in each pair of rollers are spaced apart fromone another at a distance which is slightly less than the width of theboard such that pressure is applied to the board as it passes betweenthe rollers.

Each heated roller preferably has a temperature of 300° F. to 495° F.and the board preferably moves over the rollers at a speed of 60 ft/minto 120/ft/min. Preferably, the temperature of the second roller deviceis 120° F. to 160° F.

Embodiments of our method may also including milling the cut edges suchthat each edge is perpendicular to the top surface and perpendicular tothe bottom surface of the foam board prior to passing the board betweenthe heated rollers.

Embodiments of our machine may also include a spacing mechanism attachedto at least one of the rollers in each pair of rollers. The spacingmechanism is configured to change the spacing between the rollers ineach pair of rollers. It should be appreciated that such changes inspacing can permit the machine to seal edges of boards that havedifferent widths.

A controller may be included in the machine. The controller may beconnected to the heating elements and motors or other components of themachine that control the temperature or rotational speed of the rollersor control other machine functions.

Other details, objects, and advantages of the invention will becomeapparent as the following description of certain present preferredembodiments thereof proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings we have shown certain present preferredembodiments of our machine for sealing cut edges of a foam board andmethod of sealing cut edges of a foam board in which:

FIG. 1 is a perspective view of a portion of a foam board that has cutedges prior to the cut edges being sealed.

FIG. 2 is a top view of the first present preferred embodiment of ourmachine.

FIG. 3 is a cross-sectional view of the first present preferredembodiment of our machine taken along line III-III in FIG. 2.

FIG. 4 is a fragmentary top view of a present preferred roller device.

FIG. 5 is a cross-sectional view of the first present preferredembodiment of our machine taken along line V-V in FIG. 2.

FIG. 6 is a perspective view of a roller that may be used in ourmachine.

DETAILED DESCRIPTION OF PRESENT PREFERRED EMBODIMENTS

A first present preferred foam board 1 is shown in FIG. 1. The board 1is cut from a sheet of foam material to form the foam board. The foamboard has a top surface 5, a bottom surface 6 and two cut longitudinaledges 3 and two cut ends 8. The top and bottom surfaces have a skinwhich is formed during manufacture of the foam sheet. The ends 8 and cutlongitudinal edges 3 have a rough surface resulting from cells havingbeen cut when the boards were cut from the foam sheet. Depending uponthe material used and the method for making the foam, the cells may besimilar in size or the cell diameters may vary. Foam made by the Cekulaprocess tends to have cells that vary in size. Foam made using a freefoam process tends to have a more uniform cell size. The size of thecells and variation of cell size will determine how rough the cut edgesappear to be to the casual observer.

We provide a method and machine 21 shown in FIGS. 3 through 6 forsealing the cut longitudinal edges of a foam board. The machine 21includes a milling device 22, an optimal belt feeder 25, a first pair ofrollers 26 and a second pair of rollers 30 all of which may be on asingle frame 15. The machine also includes a guide mechanism 34 betweenthe first and second pairs of rollers 26, 30. The guide mechanism 34 mayinclude guide rollers 35 or a moveable elongated member such as aconveyer belt (not shown).

When foam boards are cut from foam sheet, the cut edges of the foamboard may be concave or sloped rather than straight because the foam mayhave been warm or the blade was at an angle when the board was cut.Uneven edges may also be the result of wear on the cutting blade. If thecut edge is not square relative to the board faces, the edge will bemore difficult to seal. Therefore, we prefer to provide a milling device22 positioned to engage the cut edges of a foam board prior to the foamboard passing between the first pair of rollers 26. This device willcorrect any edges that are not straight and square. The milling device22 includes blade assemblies or grinding assemblies 23 that cut or grindthe cut edges of a foam board so those cut edges are straight. The bladeassemblies 23 may include one or more rotary blades, a shearingmechanism, grinder, abrasive roller or other cutting or grindingmechanism. The milling device 22 cuts or grinds foam boards so that thecut edges of the boards are perpendicular to the top and bottom surfacesof the board and straight along their length. Typically only a smallamount of material will be removed from the cut edges to make themstraight and square.

An optimal feeder 25 may be provided to feed foam boards into the pairof rollers 26 such that the cut edges of the foam board are oriented toengage the rollers. The feeder may also be positioned before the millingdevice 22 or between the guide mechanism 34 and the second pair ofrollers 30 to help ensure the foam boards are properly aligned whenpassing along the milling device 22 and over the rollers 26, 30.

The first pair of rollers 26 are spaced apart from one another at adistance which is slightly less than the width of the board passingbetween them. Each roller 26 has a drive mechanism 40, such as a motor.The drive mechanism 40 rotates the roller 26. The spacing between eachpair of rollers may be adjusted to engage boards of different widths.The first pair of rollers 26 is heated so that when the cut edges of afoam board pass along the rollers, the heat and pressure applied by therollers soften or preheat the edge to be sealed. Sealing occurs when thesoftened edge passes over the second set of rollers 30. The rollers 26,30 should rotate at a speed sufficient to form a seal on the cut edgesof the foam board. Material is not removed from the board by therollers. The width of the foam board is not changed significantly by therollers, even though the rollers apply pressure to the cut edges.

Heat and pressure applied by the rollers and the speed of the boardpassing over the rollers must be controlled to ensure that the cut edgesof foam boards are adequately sealed. It was found that if the speed andtemperature are not within a narrow range a smooth edge will not beformed, or plastic may stick to and build up on the rollers or flashingmay form on the corners of the board between the top and bottom facesand the edge being sealed. If the temperature and speed of the rollersof the first roller device are not hot enough or not fast enough, thecut edges also may not be adequately sealed. Furthermore, the speed andtemperature combination must be such that all portions of the edge aresealed regardless of the diameter of the cells. Therefore, the processmust work for boards made by the free foam method as well as boards madeusing the Celuka process.

In view of the operating issues that can prevent an adequate seal frombeing formed on the cut edges of a foam board, testing was conducted ona prototype machine built by Paratus Industries. Foam boards were run atdifferent combinations of roller speed and roller temperature of thefirst pair of rollers to identify speed and temperature values thatprovide acceptable sealed edges. After each board was run through theprototype machine, the cut edge was inspected to determine if thequality of the seal on the cut edge was acceptable. The seal wasconsidered to be acceptable if a pencil mark made on the edge could beeasily rubbed off. We were also concerned that the machine operated at aspeed that could keep up with board production. The chart below providesthe results of this testing:

Roller Speed For Rollers Roller Of First Roller Device Temperature SealQuality (ft/min) (Degrees F.) Acceptability 60 300 Yes 80 300 No 100 300 No 60 400 No 80 400 Yes 100  400 No 60-80 425 Yes 60-80 450 Yes 90-120 475-495 Yes 60 500 No 80 500 No 100  500 No

Based on the experimentation that was conducted, it was determined thatthe most preferred roller speed for the rollers is 90 to 120 ft/min withthe first pair of rollers at a temperature of 475-495° F. However,roller speeds ranging from 60 to 120 ft/min were acceptable based ondifferent roller temperatures. The higher speeds are preferred becausemore boards can be sealed during a production period. Furthermore, at 60ft/min acceptable seals were obtained at 300° F. and 425° F. but not at400° F. or 500° F. suggesting that a speed of 60 ft/min should not beused. Problems encountered which created unacceptable seal quality wereflashing, inadequate sealing and accumulation of plastic material on therollers. We have found that the time and temperature combinations can beused on foam boards having cell sizes ranging from 0.15 mm to 0.26 mm.Furthermore, one can use these combinations for foams made by the freefoam process or the Cekula process.

A spacing mechanism 42 may be attached to the pair of rollers 26. Thespacing mechanism includes pistons 44 to adjust the position of at leastone of the rollers. One could use other devices such as a chain drive orbelt drive in the spacing mechanism.

The guide mechanism 34 is positioned between the first roller device 26and the second roller device 30 to guide the foam boards from the firstroller device 26 to the second roller device 30. The guide rollers 35may be nip rollers or other rollers that are configured to freely rotateor be driven at a rotational speed to help move foam boards passingalong the guide mechanism.

The second pair of rollers 30 are aligned with the first pair of rollers26. The second pair of rollers 30 may be at room temperature or may beheated to a temperature that is lower than the temperature of rollers ofthe first roller device 26 to help cure the seal formed on the cut edgesby the rollers of the first roller device. Preferably, the rollers inthe second pair of rollers 30 are heated to 120° F. to 160° F. Therollers in the second pair of rollers 30 may rotate at the same speed asthe rollers 26 of the first pair of rollers or may rotate faster thanthe rollers of the first pair of rollers.

We have concluded from our testing that the primary function of thefirst set of rollers is to soften or pre-heat the polymer along the edgethat is to be sealed. The first set of rollers does not actually closeany cells, it is the second set of rollers that actually does thesealing work. As an example of this, we have run boards through thesealing machine and purposely prevented the second set of rollers fromengaging. That resulted in a very rough and totally non-sealed edge.

The function of the second set of rollers is to press or squash thecells closed. The polymer has been raised above it's glass transitiontemperature by the first set of rollers and is then moved into place andits plastic is memory re-set by the second set of rollers. Thetemperature of this second set of rollers is also far more important andnarrow-ranged than the first set. If the temperature is too high thesecond set of rollers is not able to reset the plastic memory and thepolymer will return to its pre-sealed rough state. Accordingly, thesecond set of rollers performs two functions, moving soft and mobilepolymer into a smooth state and resetting or freezing memory.

There may be instances where the foam board shown in FIG. 1 has beenmilled or cut such that the top surface 5 or bottom surface 6 or bothare not smooth. For such instances when the top surface 5 and/or thebottom surface 6 as well as the edges 3 are rough, a second set ofroller pairs may be provided to seal the top surface and/or bottomsurface as well as the edges. The second set of roller pairs may besimilar to roller pairs 26 and 30 rotated ninety degrees and are shownin dotted line in FIG. 2. The first pair of rollers 51 is heated to atemperature of from 475° F. The second pair of rollers is heated to 120°F. to 160° F. Guide rollers 53 may be provided between these pairs ofrollers. In FIG. 2, we show the second set of roller pairs 51, 52positioned off the first set of roller pairs 26, 30. However, the secondset of roller pairs may be integrated with the first set of rollerpairs. Such integration would result in roller pair 51 being adjacentrollers 26 and roller pair 52 being adjacent rollers 30. In eitherconfiguration, the rollers should cause the foam board to travel at aspeed of 90 ft/min to 120 ft/min.

We may provide a raised or lowered indicia 50 on either or both of therollers in the second pair of rollers 30. This marking may be a logo ortrademark that can be embossed on the sealed cut edges of a foam boardor could be a lot number or other marking. When the board passes overthe roller, the edge is marked with the indicia. Such an embossment ispreferably sized and configured to be apparent from close distances butunobserved from far distances so that an observer of a structure that isbuilt with such boards will not see the embossment unless standing veryclose to the boards.

A spacing mechanism 43 may be attached to one or both of the rollers ofthe second pair of rollers 30. This spacing mechanism 43 may operatesimilarly to the spacing mechanism 42 connected to the first pair ofrollers 26.

The machine 21 also may include at least one controller 57. Thiscontroller may control the speed of the motors that turn the rollers 26,30 as well as control the heating elements that heat the rollers.

Of course, other variations of the present preferred embodimentsdiscussed above may be made. For example, embodiments of our machine caninclude a conveyor belt that helps move foam boards along the rollerdevices of the machine. As yet another example, embodiments of ourmachine may include rollers that are configured to only form a sealededge on one side or edge of a foam board.

Our machine and method can be used for any foamed or cellular productthat is thermoplastic in nature. This would include polyvinyl chlorideand the olefins such as low density polyethylene, high densitypolyethylene and polypropylene. The boards may have been made by anyprocess. However, at the time of our invention, the open foam processand Cekula process were the techniques being used by major manufacturersto make foam boards.

While we have shown and described certain present preferred embodimentsof our apparatus for edge sealing foam boards and have illustratedcertain present preferred methods edge sealing foam boards and makingand using machines for edge sealing foam boards, it is to be distinctlyunderstood that the invention is not limited thereto but may beotherwise variously embodied and practiced within the scope of thefollowing claims.

1. A machine for sealing cut edges of a foam board, the foam boardhaving a top surface, a bottom surface, the cut edges comprising a firstlongitudinal cut edge extending between the top surface and the bottomsurface and a second longitudinal cut edge extending between the topsurface and the bottom surface, the machine comprising: a first pair ofspaced apart rollers, such that a foam board having a known width maypass between the first pair of rollers and the rollers are spaced apartfrom one another a distance that is less than the width of the foamboard, and each roller capable of rotating at a speed so that the foamboard will pass between the first pair of rollers at a speed of at least60 ft/min, the first pair of rollers heated to a temperature sufficientto soften the cut edges of the foam board; and a second pair of spacedapart rollers aligned with the first pair of spaced apart rollers, therollers in the second pair of rollers being spaced apart a distance suchthat the rollers will engage the first and second cut edges of the foamboard as the foam board passes between the second pair of rollers, thesecond pair of rollers each having a temperature that is lower than thetemperature of the first pair of rollers.
 2. The machine of claim 1wherein the temperature of the rollers in the first pair of rollers isbetween 300° F. to 495° F.
 3. The machine of claim 1 wherein rollers inthe first pair of rollers rotate at a speed so that the foam board willpass between the first pair of rollers at a speed of between 60 ft/minand 120 ft/min.
 4. The machine of claim 1 wherein the temperature of therollers in the second pair of rollers is between 120° F. and 1606° F. 5.The machine of claim 1 also comprising a feeder aligned with the firstpair of rollers and configured to feed the foam board to a positionbetween the first pair of rollers.
 6. The machine of claim 1 alsocomprising a milling device aligned with the first pair of rollers, themilling device positioned to engage and mill the cut edges so that thefirst and second cut edges are perpendicular to the top surface andperpendicular to the bottom surface of the foam board.
 7. The machine ofclaim 1 also comprising a spacing mechanism attached to at least one ofthe rollers of the first pair of rollers, the spacing mechanismconfigured to change spacing between the rollers in the first pair ofrollers.
 8. The machine of claim 1 also comprising a spacing mechanismattached to at least one of the rollers of the second pair of rollers,the spacing mechanism configured to change spacing between the rollersin the second pair of rollers.
 9. The machine of claim 1 also comprisingat least one motor connected to at least one of the rollers in the firstpair of rollers and one of the rollers in the second pair of rollers.10. The machine of claim 9 further comprising at least one controllerthat is connected to the at least one motor.
 11. The machine of claim 1wherein the machine is further comprised of a moveable belt positionedadjacent the rollers of the first pair of rollers.
 12. The machine ofclaim 1 wherein at least one roller in the second pair of rollers has anindicia positioned to imprint an edge of a foam board passing over theat least one roller.
 13. A machine for sealing cut edges of a foamboard, the foam board having a top surface, a bottom surface, the cutedges comprising a first longitudinal cut edge extending between the topsurface and the bottom surface and a second longitudinal cut edgeextending between the top surface and the bottom surface, the machinecomprising: a first pair of spaced apart rollers, such that a foam boardhaving a known width may pass between the first pair of rollers and therollers are spaced apart from one another a distance that is less thanthe width of the foam board, and each roller capable of rotating at aspeed so that the foam board will pass between the first pair of rollersat a speed of at least 60 ft/min, the first pair of rollers heated to atemperature sufficient to soften the cut edges of the foam board; asecond pair of spaced apart rollers aligned with the first pair ofspaced apart rollers, the rollers in the second pair of rollers beingspaced apart a distance such that the rollers will engage the first andsecond cut edges of the foam board as the foam board passes between thesecond pair of rollers, the second pair of rollers each having atemperature that is lower than the temperature of the first pair ofrollers; a third pair of spaced apart rollers, at least one roller inthe third pair of rollers having a temperature of 300° F. to 495° F.;one roller in the third pair of rollers positioned to engage the topsurface of the foam board and the second roller in the third pair ofrollers positioned to engage the bottom surface of the foam board; and afourth pair of spaced apart rollers aligned within the third pair ofrollers and having a temperature that is lower than the temperature ofthe at least one roller in the third pair of rollers, one roller in thefourth pair of rollers positioned to engage the top surface of the foamboard and the second roller in the fourth pair of rollers positioned toengage the bottom surface of the foam board.